Contactless galuano-magnetro effect apparatus

ABSTRACT

A contactless galvano-magnetro effect apparatus comprised of a magneto resistance effect device which is provided with a plurality of electrodes, between which a plurality of resistance yokes are provided, at least one of the yokes being associated with a magnetic field applying means which is capable of varying the condition of magnetic field applied to the resistance yoke.

United States Patent Masuda CONTACTLESS GALVANO-MAGNETRO EFFECTAPPARATUS [72] Inventor: Noboru Masuda, Kawaguchi, Japan [73] Assignee:Denki Onkyo Co., Ltd.

[22] Filed: Nov. 30, 1970 [21] Appl. No.: 93,636

[52] US. Cl ..323/94 H, 338/32 H [51] Int. Cl. ..G05f 7/00 [58] Field ofSearch ..338/12, 32 H, 32 R; 323/94 H;

[56] References Cited UNITED STATES PATENTS 3,304,530 2/1967 Honig..324/45 X [451 June 20, 1972 Weiss et al. ..338/32 R Saraga ..324/45 XPrimary Examiner-C. L. Albritton Attorney-James E. Armstrong and RonaldS. Cornell [5 7] ABSTRACT A contactless galvano-magnetro effectapparatus comprised of a magneto resistance effect device which isprovided with a plurality of electrodes, between which a plurality ofresistance yokes are provided, at least one of the yokes beingassociatedv with a magnetic field applying means which is capable ofvarying the condition of magnetic field applied to the resistance yoke.

12 Claims, 17 Drawing Figures all P'ATENTEDJUNZO 1912 3.671 .8 54

SHEET 1 OF 4 PATENTEDwuzo I972 SHEET 2 0F 4;

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CONTACTLESS GALUANO-MAGNETRO EFFECT APPARATUS BACKGROUND OF THEINVENTION Conventional variable resistors and switching apparatus areconstructed such that their contact pieces are forced to contactcorresponding resistance portions and contacts. Consequently, suchapparatus are disadvantageous because wear due to friction and noise,such as chattering, etc. are caused by repeated contact.

The present invention is intended to provide a contactlessgalvano-magnetro effect apparatus capable of eliminating these problems.

SUMMARY The present invention provides a galvano-magnetro effectapparatus comprised of an endless circular type (including the polygonaltype) magneto resistance effect device, electrodes made of conductivematerial which are formed so that the electrodes cross at least twoportions of the device to divide the device into at least two resistanceyokes, a magnetic field applying means which is arranged to oppose to atleast one resistance yoke so that the condition of the field beingapplied is varied, and external input power supply and load circuitswhich are connected to the electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is illustratedin detail by the accompanying drawings whereof:

FIG. 1 is a front view of a contactless galvano-magnetro effectapparatus of the present invention;

FIG. 2 is a front view of the magneto resistance efiect device used inthe apparatus;

FIG. 3 is the circuit diagram of the apparatus illustrated in FIG. 1;

FIG. 4 is a front view of another embodiment of the apparatus of thepresent invention;

FIG. 5 is the circuit diagram of the apparatus illustrated in FIG. 4;

FIG. 6 is a front view of another embodiment of the apparatus of thepresent invention;

FIG. 7 is a front view of the galvano-magnetro efiect device to be usedin the apparatus shown in FIG. 6;

FIG. 8 is a cross-sectional side view of the apparatus shown in FIG. 6;

FIG. 9 is a front view of another embodiment of the apparatus of thepresent invention;

FIG. 10 is a side view of the apparatus shown in FIG. 9;

FIG. 11a and 11b are front views of embodiments of the magnetic fieldapplying means which is used in the apparatus of the present invention;

FIGS. 12, 13 and 14 are front views of embodiments of the magnetoresistance effect device used in the apparatus of the present invention;and

FIGS.15 and 16 are the circuit diagram of the apparatus shown in FIG. 6.

DETAILED DESCRIPTION Referring to FIGS. 1 to 3, there is shown baseplate 2 made of a magnetic or non-magnetic material which is fixed atchassis l, magneto resistance effect device 3 (hereinafter referred toas the "device") made of lnAs, lnSb, Ge, Si, etc. which is fixed in theform of an endless circle to the surface of base plate 2 byphoto-etching, two electrodes 4 which are oppositely arranged in theradial direction of the device 3 so that the electrodes treated by meansof metalization cross the surface of the device, a plurality ofconductive segments 5 which are arranged at equal intervals on one oftwo resistance yokes 31 and 32, which are divided by two electrodes 4and are formed so as to cross the surface of the device in the samemanner as the electrodes, a semicircular magnet 7 which opposes thedevice 3 with a clearance separating the magnet and the device, themagnet being forced to rotate by rotary shaft 6 while being energized inthe direction of its thickness, and external input power supply 8 andexternal load 9, which are connected to the electrodes.

Conductive segments 5 need not always be provided. The apparatus asshown is, however, advantageous because, if conductive segments 5 areprovided, the plurality of resistance surfaces 3r of the resistance yokeseparated by the conductive segments operate as independent elements;therefore, the resistance yokes can be operated in the same manner as anumber of magneto-resistance effect devices which are seriesconnected.

The conductive segments can be provided at unequal intervals and can bearranged so that the intervals are gradually decreased. If thus arrangedit is possible to make the resistance variation characteristics of eachresistance surface 3r uneven by varying the ratio L/W (L is the lengthand W is the width of each resistance surface 3r) and, accordingly, theresistance variation characteristic of resistance yoke 31 can be set asdesired.

The contactless galvano-magnetro effect apparatus as described aboveoperates as follows: when magnet 7 is rotated, the areas of resistanceyokes 31 and 32 of device 3 positioned opposite to magnet 7 vary, theresistance value of resistance yokes 31 and 32 vary, and the voltage tobe applied to load 9 varies.

I-Iereupon, if conductive segments 5 are arranged on one of theresistance yokes 31 and 32 as shown, the apparatus operatesadvantageously because the resistance variation of resistance yoke 31increases with the rotation of magnet 7 and it is possible to givelinearity to the output voltage characteristic by selecting the distancebetween conductive segments 5 of resistance yoke 31.

FIGS. 4 and 5 illustrate the apparatus comprised of three re sistanceyokes 31, 32 and 33 which are made up by providing three electrodes 4 atdevice 3.

In this embodiment, magnet 7, which is used as the magnetic fieldapplying means, is sector-shaped in accordance with the length of theresistance yoke so that the magnetic flux is alternately applied to tworesistance yokes 31 and 32. Load 9 is connected to power supply 8 sothat the load is parallelconnected to resistance yoke 31 of device 3.

The apparatus of this embodiment is constructed as mentioned above. Ifmagnet 7 is alternatively positioned opposite to two resistance yokes 31and 32, the voltage applied to load 9 varies.

I-lereupon load 9 can be connected to power supply 8 so that the load isparallel-connected to resistance yoke 32. The magnet can be positionedso as not to alternatively oppose both resistance yokes 31 and 32 andcan be arranged so that the magnetic flux is applied to only one ofresistance yokes 31 and 32, one end of which is the electrode connectedto intermediate output terminal 10.

In this case, the apparatus is constructed so that magnet 7 is forced toapproach or depart from resistance yoke 31 or 32 to vary the density ofmagnetic flux applied to the resistance yoke.

Furthermore, it is desirable to provide conductive segments 5 onresistance yokes 31 and 32 which are opposite to magnet 7 as mentionedabove. Thus, the resistance variation characteristic of the resistanceyoke can be set according to its intended use.

The magnetic field applying means can be a means to increase theresistance value of a variable resistance yoke, for example, resistanceyoke 31, to a value greater than that of other resistance yokes byapplying the magnetic flux to resistance yoke 31 or alternatively, itcan be a means to decrease the resistance value of the variableresistance yoke to a value lower than that of other resistance yokes.

FIGS. 6 to 8 illustrate the apparatus provided with four resistanceyokes 31, 32, 33 and 34 which are obtained by dividing device 3 withfour electrodes 4.

Each resistance yoke is designed so that its resistance value is equalto that of other resistance yokes. In this case, power supply 8 isconnected to two electrodes which are oppositely arranged in the radialdirection and load 9 is connected to the other two electrodes.

Accordingly, in this embodiment, resistance yokes 31, 32, 33 and 34 forma bridge circuit. In this embodiment, if the condition of the magneticfield, such as, for example, the magnetic flux density, which is appliedto resistance yoke 31, varies, the resistance value of resistance yoke31 varies and the voltage is applied to load 9.

The voltage applied to load 9 gradually increases and decreases if theresistance value of resistance yoke 31 is gradually increased ordecreased. Accordingly, if load 9 is made as a resonance circuitconsisting of variable capacity diode 91 such as, for example, avaractor diode, the capacity of which varies with the voltage, as shownin FIG. 6, the resonance frequency of the resonance circuit can bevaried with the resistance variation of resistance yoke 31 and theapparatus of the present invention can be used as the tuner of atelevision set.

In this case, a method to change the condition of the magnetic fieldwhich is applied to resistance yoke 31 is optional. It is desirable touse the magnetic field applying means which is provided with disctypemagnet 7 which is energized in the direction of thickness, is rotatablysupported by shaft 6 and is provided with non-energized portion 71 inthe radial direction, as shown in FIGS. 6 and 8.

When using this magnet 7, it is necessary to vary the resistance valueof resistance yoke 31 along with movement of non-energized portion 71opposite to resistance yoke 31 and therefore it is necessary to arrangea number of conductive segments on resistance yoke 31 so that thedistances between conductive segments 5 becomes narrower as shown inFIG. 7.

When nonenergized portion 71 of magnet 70 moves along resistance yoke31, the total area of resistance surfaces 3r of the device which isopposite to non-energized portion 71 varies and accordingly, theresistance value of resistance yoke 31 gradually increases or decreases.

Hereupon conductive segments 5 can be provided on other resistance yokes32, 33 and 34 of device 3 as desired. Thus, the resistance value of allresistance yokes can be even regardless of the length of resistance yokeunder a special condition in which the magnetic fiux density is beingapplied; for example, every resistance yoke is fixed. However, in thisembodiment, magnet 7 has non-energized portion 71; therefore, theapparatus should be designed so that the bridge circuit is balanced whennon-energized portion 71 is positioned at a specific idle position.

This can be achieved by widening electrode 4 and by arranging it so thatthe bridge circuit is balanced when nonenergized portion 71 is forced tooppose to said electrode. In addition, it is possible to apply anothermethod; that is, the idle point of non-energized portion 71 can be setat one of the resistance yokes 32, 33 and 34 (excepting resistance yoke31) so that the resistance value ofresistance yoke 31 is equal to thatof other resistance yokes when the resistance yoke is opposed tonomenergized portion 71.

Therefore, conductive segments 5 can be provided on every resistanceyoke as shown FIG. 7 and the resistance value of a resistance yoke canbe relatively set.

When arranging rotary magnet 7 to oppose to the device 3, it isdesirable to fix plate magnet 72, which is energized in the direction ofthickness at the rear surface of base plate 2 as shown in FIG. 8, sothat thepolarity of the device side of the plate magnet 72 is differentfrom that of the device side of the rotary magnet 7. Thus, the magneticfield applied to device 3 can be even between both magnets 7 and 72.

The magnetic field applying means may be made so as to vary the magneticflux density applied to a specified resistance yoke as mentioned above.However, when rotary magnet 7 as shown in FIG. 6 is used, this magneticflux density applied to resistance yoke 31 along which non-energizedportion 71 moves while being kept opposite to the resistance yoke doesnot vary; accordingly, in this case, it is necessary to arrange a numberof conductive segments 5 at different intervals so that the resistancevalue of resistance yoke 31 varies with movement of the magnetic field.In other words, the magnetic field applying means can vary the situationand strength of the magnetic field applied to specified resistance yoke31.

Because the apparatus of this embodiment is constructed as describedabove, it can be used in various types of electric equipment. When usingit as a tuner, as mentioned before, the resonance frequency is variedonly with variation of the capacity of the diode; accordingly, theapparatus is disadvantageous because a substantially high voltage shouldbe applied to the diode in the channel of the high frequency side.

FIGS. 9 and 10 illustrate a tuner which raises the resonance frequencyby reducing the inductance of the resonance circuit.

In this embodiment, gate device 93, such as a Hall effect device, isconnected to the intermediate portion of coil 92 of resonance circuit 9,and diode 94 for the gate, which has the characteristics of the Zenerdiode, is connected to gate device 93.

Gate device 93 is set so that it operates when the tuner selects thechannel of the high frequency band and applies the operating voltage tothe diode. Diode 94 for the gate is set so that it becomes conductivewhen the gate device 93 operates and the intermediate point of the coil92 is short-circuited to electrode 4 at the output side of device 3.

The means to actuate gate device 93 is optional. A satisfactoryoperation of the apparatus can be obtained by fixing rotary plate 61 toshaft 6 so that it rotates together with magnet 7 as shown in FIG. 10,arranging magnetic material support plates 11 which are fixed at chassis1 to be opposite in parallel on the rotary plate 61, fixing the Halleffect device at support plate 11 as gate device 93 and mounting magnet73 on the part of rotary plate 61 so that the magnetic flux from magnet73 is concentrated onto Hall effect device 93 when the tuner selects thechannel of the high frequency band.

Thus, other galvano-magnetro effect devices can be used as gate device93; for example, the magneto-resistance effect device can be also used.

Hereupon, in the bridge circuit consisting of device 3, only resistanceyoke 31 can be used as the variable resistance yoke as shown in FIG. 15.Depending on the intended use of the apparatus, resistance yokes 31 and33 (or 32 and 34) in opposite positions can be used as the variableresistance yokes as shown in FIG. 16. Thus, it is advantageous becausethe bridge circuit can be greatly unbalanced.

Nonenergized portion 71 of rotary magnet 7 can be made by notchingmagnet 7 as shown in FIG. 6 or by closely contacting the non-magneticpiece to the notched portion as shown in FIG. 1 1a.

If non-energized portion 7 is made by loosely contacting thenon-magnetic piece to the notched portion, two or more nonenergizedportions 71 and 71' can be formed on one magnet 7. By this means aconvenient rotary magnet to be used in the apparatus, for example, asshown in FIG. 16, can be made.

Hereupon resistance yoke 31, used as the variable resistance yoke, canbe lengthened by providing conductive segments 5 on the resistance yoke.

FIGS. 12 to 14 illustrate device 3 in which resistance yoke 31 is madelonger than other resistance yokes 32, 33 and 34.

The width of resistance yoke 31 of device 3 shown in FIG. 12 isgradually narrowed in the direction of the opposite electrode. Since thearea and shape of resistance surfaces 3r of resistance yoke 31 aredifferent from each other, even though the distances between conductivesegments 5 of device 3 are fixed, the resistance value of resistanceyoke varies with movement of non-energized portion 71 of rotary magnet 7which is forced to oppose resistance yoke 31.

In this embodiment, the shape of resistance surfaces 3r of resistanceyoke 31 can be freely changed with the distance between conductivesegments 5; for example, the sensitive characteristic to magnetic fluxdensity of the wider resistance surface can be enlarged by setting ratioL/W of length L to width W to 1/4, whereas the sensitive characteristicof the narrower resistance surface can be reduced by setting the ratioL/W to l/4-n.

According to this embodiment, because the resistance variationcharacteristic can be freely controlled depending on the shape variationresistance surface 3r, the output characteristic of the device can bedetermined to meet the intended use, for example, to have linearity.

In the device shown in FIGS. 13 and 14, resistance yoke 31 is made longin accordance with the length of conductive segments 5 or the area anddistance. The devices of the above embodiment have the same advantagesas said device shown in FIG. 12 and all resistance yokes 31, 32, 33 and34 can be made in the same width; accordingly, the length of resistanceyoke 31, which is used as the variable resistance yoke, can be freelydetermined and the device 3 in the same shape can be used for manypurposes merely by changing the arrangement of the electrodes.

Since the apparatus of the invention does not require mechanicalcontacts, it is not subject to poor contact due to wear of the contactsor to generation of noise, such as chattering. Since resistance yokes31, 32, 33 and 34 are made of the same material, the thermalcharacteristics of the resistance yokes are equal; accordingly, thebridge circuit will not be unbalanced because of a rise in temperatureif device 3 forms a bridge circuit. Therefore, this type of theapparatus requires no separate temperature compensating means and thereare no problems even if a material of low quality thermal characteristicis used. Thus, the cost of production can be reduced.

If conductive segments 5 are formed on a resistance yoke or yokes, theoutput characteristics of the device can be freely determined and theresistance yoke which is used as the variable resistance yoke can belong; for example, the moving stroke of nonenergized portion 71 can belong when rotary magnet 7 as shown in FIG. 11a is used.

Since the resistance value and number of resistance yokes can'bedetermined depending on the arrangement of a plurality of electrodes 4,a device with different patterns of uses and output characteristics canbe easily made.

What is claimed is:

1. A contactless galvano-magnetro efiect apparatus com prised of a. amagneto-resistance effect device having an endless circular shape;

b. conductive electrodes which are arranged to cross the surface of thedevice at at least two positions so that the device is divided into atleast two resistance yokes;

c. a magnetic field applying means which is positioned opposite to thedevice so that the flux density of the magnetic field applied to atleast one resistance yoke can be varied; and

d. connections associated with the electrodes for an external inputpower supply and load, whereby the resistance value of the resistanceyoke can be varied with the variation of the flux density of themagnetic field.

2. A contactless galvano-magnetro effect apparatus according to claim 1,wherein at least one conductive segment, which crosses the surface of atleast one resistance yoke, is provided.

3. A contactless galvano-magnetro effect apparatus according to claim 2,wherein a plurality of conductive segments are arranged on theresistance yoke so that the distances between adjacent conductivesegments are successively decreased from one electrode in the directionof the other electrode.

4. A contactless galvano-magnetro effect apparatus according to claim 1,wherein at least one resistance yoke, the width of which is graduallyreduced from one electrode toward the other electrode, is provided.

5. A contactless galvano-magnetro effect apparatus according to claim 1,wherein a circular magnetro-resistance effect device is provided withthree electrodes and is divided into three resrstance yokes, two of theelectrodes being connectable between the remaining intermediateelectrode and the power supply, so as to be parallel with one of tworesistance yokes which has the intermediate electrode at one end, and amagnetic field applying means which is positioned opposite to one of tworesistance yokes divided by the intermediate electrode.

6. A contactless galvano-magnetro effect apparatus according to claim 5,wherein the flux density of the magnetic field applied to the tworesistance yokes which are divided by the intermediate electrode isalternately varied.

7. A contactless galvano-magnetro effect apparatus according to claim 1,wherein a circular device is provided with four electrodes and isdivided into four resistance yokes, the power supply being connected totwo of the four electrodes which extend opposite from each other, theload being connected to the remaining two electrodes, and the resultingbridge circuit, which consists of the four resistance yokes, isunbalanced by varying the flux density of the magnetic field applied toone of the resistance yokes, and the voltage isapplied to the load.

8. A contactless galvano-magnetro effect apparatus according to claim 7,wherein the flux density of the magnetic field applied to the tworesistance yokes corresponding to the two opposite yokes of the bridgecircuit is varied at the same time.

9. A contactless galvano-magnetro effect apparatus according to claim 7wherein the load connected to the bridge circuit is a resonance circuitconsisting of a variable capacity diode, which varies its capacity inaccordance with voltage, and an inductance coil and the bridge circuitare controlled so that the output characteristics gradually increase ordecrease with a variation of the flux density of the magnetic field.

10. A contactless galvano-magnetro effect apparatus according to claim9, wherein a gate device and a diode for the gate with Zenercharacteristics are series-connected between the intermediate point ofthe coil of the resonance circuit and the output terminal of the bridgecircuit, the gate device operating to cause the diode for the gate to beconductive and the intermediate point of the coil being short-circuitedto the output terminal of the bridge circuit when the flux density ofthe magnetic field changes into a specified pattern.

11. A contactless galvano-magnetro effect apparatus according to claim10, including a rotary shaft wherein a rotary magnet, energized in thedirection of thickness, is provided with at least one non-energizedportion in the radial direction and rotates in parallel with the device,a rotary plate, to which the magnet is fixed, is mounted to the samerotary shaft, and a fixed support plate is provided with at least onegalvano-magnetro effect device as the gate device and is arrangedopposite to the rotary plate, the magnetic flux from the magnet on therotary plate being concentrated onto the gate device of the supportplate when the non-energized portion of the rotary magnet comes to aposition opposite to a specified position of a specific resistance yokeof the device.

12. A contactless galvano-magnetro effect apparatus according to claimI, wherein a rotary magnet is energized in the direction of thicknessand is provided with at least one nonenergized portion in the radialdirection so that the non-energized portion moves opposite to theresistance yoke of the device.

1. A contactless galvano-magnetro effect apparatus comprised of a. amagneto-resistance effect device having an endless circular shape; b.conductive electrodes which are arranged to cross the surface of thedevice at at least two positions so that the device is divided into atleast two resistance yokes; c. a magnetic field applying means which ispositioned opposite to the device so that the flux density of themagnetic field applied to at least one resistance yoke can be varied;and d. connections associated with the electrodes for an external inputpower supply and load, whereby the resistance value of the resistanceyoke can be varied with the variation of the flux density of themagnetic field.
 2. A contactless galvano-magnetro effect apparatusaccording to claim 1, wherein at least one conductive segment, whichcrosses the surface of at least one resistance yoke, is provided.
 3. Acontactless galvano-magnetro effect apparatus according to claim 2,wherein a plurality of conductive segments are arranged on thEresistance yoke so that the distances between adjacent conductivesegments are successively decreased from one electrode in the directionof the other electrode.
 4. A contactless galvano-magnetro effectapparatus according to claim 1, wherein at least one resistance yoke,the width of which is gradually reduced from one electrode toward theother electrode, is provided.
 5. A contactless galvano-magnetro effectapparatus according to claim 1, wherein a circular magnetro-resistanceeffect device is provided with three electrodes and is divided intothree resistance yokes, two of the electrodes being connectable betweenthe remaining intermediate electrode and the power supply, so as to beparallel with one of two resistance yokes which has the intermediateelectrode at one end, and a magnetic field applying means which ispositioned opposite to one of two resistance yokes divided by theintermediate electrode.
 6. A contactless galvano-magnetro effectapparatus according to claim 5, wherein the flux density of the magneticfield applied to the two resistance yokes which are divided by theintermediate electrode is alternately varied.
 7. A contactlessgalvano-magnetro effect apparatus according to claim 1, wherein acircular device is provided with four electrodes and is divided intofour resistance yokes, the power supply being connected to two of thefour electrodes which extend opposite from each other, the load beingconnected to the remaining two electrodes, and the resulting bridgecircuit, which consists of the four resistance yokes, is unbalanced byvarying the flux density of the magnetic field applied to one of theresistance yokes, and the voltage is applied to the load.
 8. Acontactless galvano-magnetro effect apparatus according to claim 7,wherein the flux density of the magnetic field applied to the tworesistance yokes corresponding to the two opposite yokes of the bridgecircuit is varied at the same time.
 9. A contactless galvano-magnetroeffect apparatus according to claim 7 wherein the load connected to thebridge circuit is a resonance circuit consisting of a variable capacitydiode, which varies its capacity in accordance with voltage, and aninductance coil and the bridge circuit are controlled so that the outputcharacteristics gradually increase or decrease with a variation of theflux density of the magnetic field.
 10. A contactless galvano-magnetroeffect apparatus according to claim 9, wherein a gate device and a diodefor the gate with Zener characteristics are series-connected between theintermediate point of the coil of the resonance circuit and the outputterminal of the bridge circuit, the gate device operating to cause thediode for the gate to be conductive and the intermediate point of thecoil being short-circuited to the output terminal of the bridge circuitwhen the flux density of the magnetic field changes into a specifiedpattern.
 11. A contactless galvano-magnetro effect apparatus accordingto claim 10, including a rotary shaft wherein a rotary magnet, energizedin the direction of thickness, is provided with at least onenon-energized portion in the radial direction and rotates in parallelwith the device, a rotary plate, to which the magnet is fixed, ismounted to the same rotary shaft, and a fixed support plate is providedwith at least one galvano-magnetro effect device as the gate device andis arranged opposite to the rotary plate, the magnetic flux from themagnet on the rotary plate being concentrated onto the gate device ofthe support plate when the non-energized portion of the rotary magnetcomes to a position opposite to a specified position of a specificresistance yoke of the device.
 12. A contactless galvano-magnetro effectapparatus according to claim 1, wherein a rotary magnet is energized inthe direction of thickness and is provided with at least onenon-energized portion in the radial direction so that the non-energizedportion moves opposite to the resistance yoke of the device.